The ADC used for this project has 8 analog inputs, we only used 3 per board. However, I've added 3 additionals 10K pulldown resistors with the corresponding cabling to each board, so a total of 6 inputs per board can be used (sorry for the remaining 2, I just ran out of 10k resistors...)
The wire pairs left hanging can thus be connected to any analog device (potentiometer, LDR, FSR...). One conductor is hooked to a MCP3208 input pin (you'll have to experiment a bit to find which one), the other to the 3V3, so the sensor can be directly soldered accross a pair. The pairs are soldered in the order of the MCP3208 pins on the ribbon cable (in0-3v3, in1-3v3, ..., in5-3v3)

Code-wise, only two modifications will allow the system to adapt to the additionnal inputs :
in MCP3208.ino circa l65 : set inputsCount to the desired number (eg. 4 will use the already cabled 3 LDR on MCP's A0, A1 & A2 plus the dangling pair connected to A3)
in OLOwrapper.py circa l56 : in expectedOSCmessages, set the "count" of the device to the same number as above

Of course, more modules (D1+MCPs) can be added, simply remember to change their OSCaddress in MCP3208.ino circa l27 to avoid conflicts, and add them to OLOwrapper.py circa l56 in expectedOSCmessages.

Have fun !